JSON, or JavaScript Object Notation, is officially defined here. It is the standard data interchange format for web APIs.

The GA4GH Web API uses a JSON wire protocol, exchanging JSON representations of the objects defined in its Protocol Buffers schemas. More information on the schemas is available in Google Protocol Buffers; basically, the Protocol Buffers type definitions say what attributes any given JSON object ought to have, and what ought to be stored in each of them.

The GA4GH web APIs use Protocol Buffers IDL to define their schemas, and use the associated Google Protocol Buffers JSON serialization libraries. Notice that the Protocol Buffers IDL uses snake case, while the on-the-wire protocol is in camel case.